Joint fill composition and method

ABSTRACT

A composition and method for protecting pipeline joints is disclosed. A mold covers the exposed pipeline joint. A reaction composition including a polyol, an isocyanate, and an ester, preferably 2,2,4-trimethyl-1,2-pentanediol diisobutyrate, is added to the mold and allowed to react to form a polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. Ser. No. 10/801,164 filed onMar. 5, 2004.

This application claims the benefit of U.S. Provisional Application No.60/452,706 filed Mar. 7, 2003, and U.S. Provisional Application No.60/452,765 filed Mar. 7, 2003, both of which are hereby incorporated byreference in their entirety for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a composition and method for protectingpipeline joints. More particularly, the invention relates to acomposition and a method for infilling the space at a welded joint in acoated (ex. concrete, polyethylene, etc.) pipeline between the ends ofthe coating on sequential joints of pipe.

2. Description of the Related Art

Offshore pipelines larger than about 12 inches in diameter are commonlycoated with a thick layer of concrete to weight the pipeline down in thewater. Such concrete coatings or weight coatings are applied toindividual lengths of the pipe with the coating extending the fulllength of the pipe except for several inches near each end. Prior toapplying the concrete coating, the pipe lengths are usually coated witha material, such as epoxy, to protect the pipe from corrosion. Thiscoating material is also terminated several inches from each end.Successive lengths of pipe are joined together by welding, leaving a gapin the coating material and in the concrete covering at each joint.

It is the usual practice to apply a coating to the pipe in this gap toprotect the pipe against corrosion, for example with a hot fusion bondedepoxy and/or a shrink sleeve, and to fill the gap between the ends ofthe oncrete coatings so as to provide a smooth, uninterrupted coveringfor the pipeline. The pipeline can then move smoothly over the pipelinelay barge or vessel rollers and down the stinger to the sea bed.

The gaps in the pipeline have been filled with various materials byvarious techniques. One procedure that has been used is to place a metalsleeve or mold over the gap and fill the sleeve with molten mastic whichsolidifies as it cools. However, in most cases the pipeline must be in acondition for handling immediately after the gaps are filled, so thatthe laying of the pipeline can proceed without delays. The masticfilling does not set to a sufficiently strong material within therequired time to allow further processing of the pipe without additionalreinforcement to protect the mastic. Therefore, in conventional fillingoperations where mastic is used, the sleeve is left in place, so that itremains on the pipe on the ocean floor. This is objectionable, since thesleeve can snag fishnets, and cause other damage to marine operations.Moreover, the filling of the gaps with mastic in this way is highlylabor intensive, and therefore expensive.

Another method that has been used to fill the gaps in concrete coatedpipeline joints utilizes a fast cure material inside a removable moldwhich is removed before the pipe is advanced into the water. Variouspolymer concretes, such as those disclosed in U.S. Pat. No. 4,608,280,or polyurethanes have been used in this way. The removable mold surfaceis coated with a release agent to prevent the fast cure material fromsticking to the mold surface. Such a mold release adds expense andprocessing time, and is inefficient if improperly applied. Furthermore,some of the release material remains on the surface of the fast curematerial and enters the water with the pipe as a potential environmentalcontaminant.

Other techniques replaced the mastic filler with other types ofmaterials. In the methods disclosed in U.S. Pat. No. 5,328,648 and U.S.Pat. No. 5,489,405, the exposed portion of pipe was covered with a moldwhich was then filled with a filler material. The filler materialsincluded granular or particulate matter having between about 1/16 inchto 1 inch diameter such as gravel, iron ore, wood chips, etc. whichwould not pack solidly or uniformly. Elastomeric polymers were theninjected into the mold in an attempt to fill the interstices between thegranular fill materials. The preferred polymers included rapid settingsolid polyurethanes, as for example those prepared by the reaction ofthe polyhydroxyl containing compounds and the organic polyisocyanatesdescribed in U.S. Pat. Nos. 3,983,064, 4,154,716, and 4,246,363. Afterthe polymer components had reacted completely the mold would be removedfrom the surface of the infill. The elastomeric polymers used in thismethod included a liquid modifier consisting primarily of aromatichydrocarbons. The use of aromatic hydrocarbons in this application hasseveral disadvantages including air and marine environmental and safetyissues.

Another technique, disclosed in U.S. Pat. No. 4,909,669, involvedwrapping the exposed portions of pipe with a thermoplastic sheet. Thesheet overlapped the ends of the weight coat adjacent the exposed jointand was then secured in place by screws, rivets, or straps. To increasethe rigidity and impact resistance this joint protection system requiredthe installation of reinforcing members such as plastic bars or tubes tothe interior of the sheet. The reinforcement bars or tubes either had tobe precut and stored on the barge or else cut to the required fittingform as part of the installation process on the barge. This requiredadditional handling and made the installation process more difficult.

Another method of reinforcing this joint protection system was to fillthe lower portion of the annular space between the pipe and the plasticsheet with a material such as pre-formed foam half shell. When foam halfshells were used in the lower portion of the annular space to providesupport, the upper portion of the joint and the corrosion coating was ineffect protected only by the plastic sheet enclosing the upper portionwhich had no foam covering. This could cause a particular problem if thepipelines were located where they would encounter the drag lines ortrawler boards attached to the nets of fishing trawlers. The corrosioncoating on the upper portion of the pipe joint could become damaged bythis type of towed object. An additional problem with this jointprotection system occurred when pipelines were laid in shallow waters,i.e., less than about 200 feet deep. Pipelines in shallow waters wereoften buried by using high pressure water jets which were directed atthe ocean floor where the pipelines were to be buried. The water jetswould wash out a trench into which the pipelines would be dropped forburial. The joint protection system could be damaged when the water jetscame in contact with the pipeline joint because the plastic sheet overthe top of the pipe joint was not reinforced.

Another method for protecting exposed pipeline joint sections, disclosedin U.S. Pat. Nos. 5,900,195 and 6,402,201, begins by forming a pliablesheet of cover material into a cylinder which is fitted over the exposedportions of the joint connection. The longitudinal end portions of thepliable sheet of cover material overlap the adjacent edges of the weightcoating. Side edge portions of the sheet of cover material forming thecylinder are then overlapped tightly such that an annular pocket isformed about the exposed joint section. The outside side edge is thensealed to the surface of the sheet of cover material, completelyencasing the exposed pipe and the annular pocket or space. Polyurethanechemicals are then injected into the empty annular space where theyreact to form a high density foam which fills the annular space. Thecover material remains part of the joint fill and is not removed.

BRIEF SUMMARY OF THE INVENTION

The present invention includes an improved composition and method forinfilling the gaps in pipelines having thick coatings, such as offshorepipelines formed from the concrete coated pipe using the improvedcomposition. The preferred composition of the present invention includespolyol, isocyanate, and diluent. The diluent is preferably an esterdiluent. More preferably, the composition includes an A-side componentincluding polymeric MDI and 2,2,4-trimethyl-1,2-pentanedioldiisobutyrate (sold by Eastman Chemical Company under the trademarkTXIB), and a B-side component including a polyol, catalyst, water, TXIB,and surfactant. This preferred composition forms a foam having a highdegree of open cells. Other preferred compositions can be used toproduce non-foamed elastomer or solid polymers by excluding water (orother blowing agents) from the composition.

The preferred method of the present invention includes enclosing a moldaround the exposed pipeline portion or gap, introducing the improvedcomposition, and allowing the composition to react and form a polymer.The polymer formed by the reaction composition is preferably an opencelled foam, but can be an elastomer, or a solid polymer depending uponthe specific components utilized. The method of the present inventioncan include a variety of techniques and materials to form the mold. Themold can be reusable or remain part of the gap pipeline jointprotection.

DETAILED DESCRIPTION OF THE INVENTION

The present invention includes an improved composition and a method forinfilling the gaps in pipelines having thick coatings, such as offshorepipelines formed from the concrete coated pipe.

The Composition

Generally, the composition comprises a polyol component (B-side), anisocyanate component (A-side), an ester component. The ester can bepresent in either the A-side, the B-side, or both. The combination ofthe ester with the polyol and isocyanate results in a reaction producthaving improved properties as compared to the polyurethane systems usedin the joint infill systems of the prior art.

The ester is preferably a diester, and most preferably exemplified by,but not limited to, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (soldby Eastman Chemical Company under the trademark TXIB). TXIB is notreported to be a marine pollutant and does not have the same negativeimpact compared to the aromatic hydrocarbons of the prior art. The esterpreferably is present in a range of from about 10 weight % to about 40weight % of the total composition. The ester is more preferably presentin the range of from about 25 weight % to about 40 weight %. Allcomposition percentages disclosed herein are weight % unlessspecifically stated otherwise.

The isocyanate component of the composition can include isocyanates,polyisocyanates, or isocyanate prepolymers. Preferably, the isocyanatecomponent is a polyisocyanate. The term polyisocyanate as used hereinrefers to any isocyanate having an average functionality greater than orequal to about 2.0. The polyisocyanate is preferably based ondiphenylmethane diisocyanates such as those obtainable byaniline/formaldehyde condensation followed by phosgenation (“polymericMDI”) or derivatives of these polyisocyanates which may containcarbodiimide, biuret, urethane, isocyanurate, allophanate groups, andmixtures of compounds having these groups, and are liquid at roomtemperature. Preferred polyisocyanates are exemplified by, but notlimited to, polymeric MDI sold by Bayer under the trademark MONDUR MR,by BASF under the trademark LUPRANATE M20S, by The Dow Chemical Companyunder the trademark PAPI 27 or by Huntsman Chemical under the trademarkRUBINATE M.

Alternatively, an isocyanate homopolymer can be used in the compositionif it is desired to produce an elastomeric joint fill system.Elastomeric joint fill systems may be desired for example in pipelinesof lower diameter that have some flexibility. A preferred polyisocyanatehomopolymer for the preparation of a elastomeric joint fill isexemplified by, but not limited to, a 143 equivalent weight modified4,4′-diphenylmethane diisocyanate such as MM 103 sold by BASF, MONDUR CDsold by Bayer, ISONATE 143L sold by The Dow Chemical Company or R 1680sold by Huntsman Chemical.

Alternatively, an isocyanate prepolymer can be used in the compositionif it is desired to produce an elastomeric joint fill system. Preferredprepolymers include, but are not limited to MONDUR PF sold by Bayer,ISONATE 181 sold by The Dow Chemical Company, or R 1209 sold by HuntsmanChemical.

The polyol component of the composition can include a variety of polyolsincluding polyether polyols, polyester polyols, or combinations. In thepreferred embodiment, the polyol is a polyether polyol or combination ofpolyether polyols. More preferably, the polyol component includes a fastreacting amine based polyol. Preferred polyether polyols are exemplifiedby, but not limited to 40-770 (a tetrol, with a hydroxyl number averageof 770) sold by Arch Performance Urethanes and Organics, VORANOL® 800sold by The Dow Chemical Company, or QUADROL sold by BASF.

In addition to the polyol component, the isocyanate component, and theinsoluable ester, other components may be desired in various embodimentsof the composition of the present invention. Catalysts, surfactants,water, and other blowing agents are non-limiting examples of additionalcomponents.

Preferably a catalyst is used in the present invention. Preferredcatalysts for use in the composition include, but are not limited to,organic tin compounds such as tin (II) octoate, dibutyl tin dilaurate,UL-22 (sold by Witco Chemical Organics Division under the trademarkWITCO FOMREZ UL-22) or lead naphthenate (PbN); or tertiary amines suchas N,N-dimethyl cyclohexylamine (DMCHA) sold as PolyCat 8 by AirProducts & Chemicals, 1,4-diazabicyclo[2.2.2]octane (TEDA) sold underthe tradename DABCO by Air Products & Chemicals, and 70%bis(dimethylaminoethyl)ether in DPG (sold as BL-11 by Air Products &Chemicals); or amine polyol catalysts such as 33% TEDA in glycol ordimethylethanolamine (DMEA); amine catalysts such aspentamethyldiethylenetriamine (PMDETA). Other conventional amine andorganometallic catalysts known for use in polyurethane forming reactionsmay be used.

Preferably, a surfactant is used in the composition when an open celledfoam is desired. Surfactants such as the polyether polysiloxanes knownto be useful in polyurethane foam forming reactions may be used in thecomposition. Non-silicone surfactants may also be used. The non-siliconesurfactants include, but are not limited to, LK443 (sold by AirProducts). Suitable surfactants may be obtained from GoldschmidtChemical, Air Products & Chemicals, Inc., Witco or others. Preferredsurfactants for use in the composition include Y-10762 sold by OSI,B8423, B8934, and B8935 sold by Goldschmidt Chemical. A small amount ofaromatic hydrocarbon can also be used to increase the open cell contentof foams.

Preferably, the composition will include water. Water, may be added in aquantity of up to about 5% by weight, preferably up to about 4% byweight, and most preferably up to about 2% by weight based on the weightof polyisocyanate. Alternatively, other blowing agents can be used incombination with or as replacements for water. Organic blowing agentsinclude, but are not limited to, non-ozone depleting hydrofluorocarbons,non-ozone depleting hydrochlorofluorocarbons and aliphatic hydrocarbons.Conventional blowing agents known for preparing water-blown andnon-water blown polyurethanes may be used. The blowing agents may beused singly or in mixtures.

U.S. Pat. No. 6,521,673 describes many of the components that aresuitable for use in the present composition. Other compositionsdescribed in this patent can be used to form closed cell or elastomericjoint fill polymers. U.S. Pat. No. 6,521,673 is hereby incorporated byreference in its entirety for all purposes.

An example of a preferred composition includes an A-side comprisingbetween about 15 weight % to about 25 weight % TXIB with the remainderof the A-side being polymeric MDI. The B-side of this preferredcomposition comprises about 35 weight % to about 45 weight % of an aminebased polyether polyol, about 50 weight % to about 65 weight % TXIB,about 0.25 weight % to about 2.00 weight % surfactant, about 75 weight %to about 1.5 weight % water, and a combination of amine catalyst and tincatalyst of less than about .2 weight percent. In this preferredembodiment, the A -side comprises about 50 weight % to about 60 weight %of the total composition and the B-side comprises about 40 weight % toabout 50 weight %. Preferably, the components of this preferredcomposition are reacted to produce a foam that has a free rise densityof between about 4 and about 8 pounds/cubic foot, most preferably about6 pounds/cubic foot, and a packed in the mold density of between about 7and about 12 pounds/cubic foot, most preferably about 9-10 pounds/cubicfoot. Preferably, the components of this preferred composition arereacted to produce a foam that has an open cell content of greater thanabout 50%, more preferably greater than 80%, and most preferably greaterthan 90%.

The following non-limiting examples demonstrates preferred compositionsfor filling gaps on weight coated pipes.

EXAMPLE 1

A experimental pipe joint infilling composition was tested including thefollowing components: B-Side Ingredients Parts by Weiqht 40-770polyether polyol 38.0 Water 1.30 Polycat 8 0.10 UL-22 0.00375 TXIB 58.00Y-10762 silicone surfactant 2.0The B-Side components were reacted with an A-side comprising 80 weight %polymeric MDI and 20 weight % TXIB. The composition comprised 54.8weight % A-side and 45.2 weight % B-side. The resulting reaction productwas an open celled polyurethane foam having a free rise density of about6 pounds/cubic foot, a packed in the mold density between 9 and 10pounds/cubic foot, and an open cell content of about 84.5%, 7.2% closedcells, and 8.2% cell walls.

EXAMPLE 2

A second experimental pipe joint infilling composition was testedincluding the following components: B-Side Ingredients Parts by Weight40-770 polyether polyol 40.0 Water 1.30 Polycat 8 0.20 Polycat 5 0.10Dabco 33LV 0.13 TXIB 57.6 Y-10762 silicone surfactant 0.8The B-Side components were reacted with an A-side comprising 85 weight %polymeric MDI and 15 weight % TXIB. The composition comprised 54.8weight % A-side and 45.2 weight % B-side giving an isocyanate index ofabout 1.10. The resulting reaction product was an open celledpolyurethane foam having a free rise density of about 6.5 pounds/cubicfoot, a packed in the mold density about 10.5 pounds/cubic foot, and anclosed cell content of about 9.0%. Parallel compressive strength wasapproximately 250-300 pounds per square inch at 10% deflection.

The Method

The preferred method of the present invention generally includesenclosing a mold around the exposed pipeline portion or gap, introducingthe reaction composition, and allowing the composition to react and forma polymer. The polymer formed by the reaction composition can be an opencelled foam or an elastomer depending upon the specific componentsutilized as discussed above.

The method begins with the installation of a mold enclosing the gaparound the pipeline joint. A variety of methods of installing or forminga mold around the gap are known in the art and can be utilized in thecurrent method. For example, various mold techniques are disclosed inU.S. Pat. No. 5,328,648, U.S. Pat. No. 5,489,405, U.S. Pat. No.5,804,093, U.S. Pat. No. 5,900,195, and U.S. Pat. No. 6,402,201. Each ofthese patents are hereby incorporated by reference in their entirety forall purposes.

After installation of the mold, the A-side and B-side components of thecomposition are added to the inside of the mold. The A-side and B-sidecomponents can be premixed, injected by a reaction head, or combined andinserted using other techniques such as would be known to a person ofordinary skill in the art. Once the composition has been added to theinside of the mold, the components are allowed to react and form apolymer. Preferably, the reaction process is quick and polymer formationis substantially complete within a few minutes time.

As one alternative step, the mold may be filled with filler materialsuch as gravel, etc. prior to addition of the reaction composition. Thecomposition will react and form polymer around the filler material andhold it in place. As an additional alternative step, a permeablemembrane may be included along the outer portion of the mold prior toaddition of the reaction components. The permeable membrane will adhereto the outer surface of the polymer when the reaction is complete andact as a protective skin to prevent damage to the polymer. Examples of apermeable membrane can include permeable polyethylene sheeting, orcoarse gauge mesh materials.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, but to the extent forseeable, thespirit and scope of the invention are defined by the appended claims.

1-12. (canceled)
 13. A method for filling a gap at the junction betweentwo lengths of coated pipe, the method comprising: enclosing the gapwith a mold having an opening; introducing a composition comprisingpolyol, isocyanate, and an ester diluent into the mold; and allowing thecomposition to react and form a polymer.
 13. (canceled)
 14. The methodof claim 13, wherein the isocyanate comprises polymeric MDI.
 15. Themethod of claim 13, wherein the ester comprises a diester.
 16. Themethod of claim 13, wherein the insoluable ester comprises2,2,4-trimethyl-1,2-pentanediol diisobutyrate.
 17. The method of claim13, wherein the composition further comprises water.
 18. The method ofclaim 13, wherein the composition further comprises hydrofluorocarbonblowing agent.
 19. The method of claim 13, wherein the compositionfurther comprises hydrocarbon blowing agent.
 20. The method of claim 13,wherein the composition further comprises a silicone based surfactant.21. The method of claim 13, further comprising the step of removing themold after formation of the polymer.
 22. The method of claim 13, whereinthe polymer comprises a polyurethane foam having an open cell content ofabout eighty percent or higher.
 23. The method of claim 13, wherein thepolymer comprises a polyurethane foam having an open cell content ofabout ninety percent or higher.
 24. The method of claim 13, wherein thepolymer comprises a polyurethane foam having a density of between about2 and about 12 pounds per cubic foot.
 25. The method of claim 13,wherein the polymer comprises an elastomeric polymer.
 26. The method ofclaim 3, wherein the isocyanate comprises an isocyanate prepolymer. 27.The method of claim 13, further comprising the step of adding fillermaterial to the mold, after the enclosing step and before the step ofintroducing the reaction composition.
 28. The method of claim 13,further comprising the step of adding a permeable membrane into the moldbefore the step of introducing the reaction composition.
 29. (canceled)30. The method of claim 13, wherein the polyol comprises an amine basedpolyether polyol.
 31. The method of claim 30, wherein the ester diluentcomprises 2,2,4-trimethyl-1,2-pentanediol diisobutyrate.
 32. The methodof claim 13, wherein the polyol comprises an amine based polyetherpolyol.